The increasing need for wideband communication systems drives an increasing demand for suitable measurement systems. For analyzing those communication systems, the obtain a measurement system having such a good jitter performance, the whole clock tree has to be stabilized.
The publication E. W. Jacobs et al., “Optically clocked track-and-hold for high-speed, high-resolution analog-to-digital conversion,” IEEE MWP '04, 2004, pages 190-192, describes a track-and-hold-unit that can be used within an analogue-to-digital-converter, wherein the track-and-hold-unit receives an optical clock. The track-and-hold-unit therefore comprises two photodiodes that are used for generating an electrical current which is fed into a diode circuit thereby turning off a lower current from two current sources. Whenever an optical pulse is received by the two photodiodes, a high frequency signal is kept constant at the output of the diode bridge.
It is a drawback of the publication that the sampling rate is limited, because the necessary hold-times for the analog/digital-converter cannot be reduced anymore.
What is needed, therefore, is an approach for a sampling device that has a very high sampling rate as well as a good jitter performance.